Commit 930e6fcd authored by Kan Liang's avatar Kan Liang Committed by Arnaldo Carvalho de Melo
Browse files

perf tools: Add time out to force stop proc map processing 



System wide sampling like 'perf top' or 'perf record -a' read all
threads /proc/xxx/maps before sampling. If there are any threads which
generating a keeping growing huge maps, perf will do infinite loop
during synthesizing. Nothing will be sampled.

This patch fixes this issue by adding per-thread timeout to force stop
this kind of endless proc map processing.

PERF_RECORD_MISC_PROC_MAP_PARSE_TIME_OUT is introduced to indicate that
the mmap record are truncated by time out. User will get warning
notification when truncated mmap records are detected.

Reported-by: default avatarYing Huang <ying.huang@intel.com>
Signed-off-by: default avatarKan Liang <kan.liang@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ying Huang <ying.huang@intel.com>
Link: http://lkml.kernel.org/r/1434549071-25611-1-git-send-email-kan.liang@intel.com


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent c05676c0

include/uapi/linux/perf_event.h

+4 −0
Original line number Diff line number Diff line
@@ -565,6 +565,10 @@ struct perf_event_mmap_page { 
#define PERF_RECORD_MISC_GUEST_KERNEL		(4 << 0)

#define PERF_RECORD_MISC_GUEST_USER		(5 << 0)



/*

 * Indicates that /proc/PID/maps parsing are truncated by time out.

 */

#define PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT	(1 << 12)

/*

 * PERF_RECORD_MISC_MMAP_DATA and PERF_RECORD_MISC_COMM_EXEC are used on

 * different events so can reuse the same bit position.

tools/perf/util/event.c

+18 −0
Original line number Diff line number Diff line
@@ -213,6 +213,8 @@ static int perf_event__synthesize_fork(struct perf_tool *tool, 
	return 0;

}



#define PROC_MAP_PARSE_TIMEOUT	(500 * 1000000ULL)



int perf_event__synthesize_mmap_events(struct perf_tool *tool,

				       union perf_event *event,

				       pid_t pid, pid_t tgid,
@@ -222,6 +224,8 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
{

	char filename[PATH_MAX];

	FILE *fp;

	unsigned long long t;

	bool truncation = false;

	int rc = 0;



	if (machine__is_default_guest(machine))
@@ -240,6 +244,7 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
	}



	event->header.type = PERF_RECORD_MMAP2;

	t = rdclock();



	while (1) {

		char bf[BUFSIZ];
@@ -253,6 +258,12 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
		if (fgets(bf, sizeof(bf), fp) == NULL)

			break;



		if ((rdclock() - t) > PROC_MAP_PARSE_TIMEOUT) {

			pr_warning("Reading %s time out.\n", filename);

			truncation = true;

			goto out;

		}



		/* ensure null termination since stack will be reused. */

		strcpy(execname, "");
@@ -301,6 +312,10 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
			event->header.misc |= PERF_RECORD_MISC_MMAP_DATA;

		}



out:

		if (truncation)

			event->header.misc |= PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT;



		if (!strcmp(execname, ""))

			strcpy(execname, anonstr);
@@ -319,6 +334,9 @@ int perf_event__synthesize_mmap_events(struct perf_tool *tool, 
			rc = -1;

			break;

		}



		if (truncation)

			break;

	}



	fclose(fp);

tools/perf/util/event.h

+1 −0
Original line number Diff line number Diff line
@@ -265,6 +265,7 @@ struct events_stats { 
	u32 nr_unknown_id;

	u32 nr_unprocessable_samples;

	u32 nr_auxtrace_errors[PERF_AUXTRACE_ERROR_MAX];

	u32 nr_proc_map_timeout;

};



struct attr_event {

tools/perf/util/session.c

+11 −0
Original line number Diff line number Diff line
@@ -1064,6 +1064,8 @@ static int machines__deliver_event(struct machines *machines, 
	case PERF_RECORD_MMAP:

		return tool->mmap(tool, event, sample, machine);

	case PERF_RECORD_MMAP2:

		if (event->header.misc & PERF_RECORD_MISC_PROC_MAP_PARSE_TIMEOUT)

			++evlist->stats.nr_proc_map_timeout;

		return tool->mmap2(tool, event, sample, machine);

	case PERF_RECORD_COMM:

		return tool->comm(tool, event, sample, machine);
@@ -1360,6 +1362,15 @@ static void perf_session__warn_about_errors(const struct perf_session *session) 
		ui__warning("%u out of order events recorded.\n", oe->nr_unordered_events);



	events_stats__auxtrace_error_warn(stats);



	if (stats->nr_proc_map_timeout != 0) {

		ui__warning("%d map information files for pre-existing threads were\n"

			    "not processed, if there are samples for addresses they\n"

			    "will not be resolved, you may find out which are these\n"

			    "threads by running with -v and redirecting the output\n"

			    "to a file.\n",

			    stats->nr_proc_map_timeout);

	}

}



static int perf_session__flush_thread_stack(struct thread *thread,

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